First of all i am kinda new, but i been reading the forums, and helping on some translations with little stuff and crape things XDXD, anyway i am going to give you guys a small guide on how to play this game and fully understand the mechanics.

First of all the Class Distribution.

Duelist 3/10 Usefulness

They are not that great of a class are not all-rounders and dont do much dmg.
The real use of the duelist is the upper echelon jump(Chaos Attack), it is used to move from 1 high to the other, always taking in consideration if the position they are, are needed by a Warrior.

Warrior 9/10

They are the most used class in the whole game and basically the only one that allows you to get Key/Manufacturing Items.
Their Warrior skills Chaos/Law are used to fast-breaking obstacles, most of the time use of Chaos Attaks for multiple attack.
They cant move but they can be stationed on the lower parts of the map to break bridges which are the only obstacles which dont appear again.
Apart from that they are great damage dealers, from 3-7k dmg depending on the lvl they are.

Knight 6/10

They are the all-around class and the one you can use to move around from place to place depending on the environment of the map, they real usage they have are for massive damage dealing, they got a very low defense and got a high mobility. The way to use them is to move around with them station them on the place the obstacle is and then end the turn, and change it with a warrior to break the obstacle.
Their damage dealing is the highest going from 4-11k in one blow(10-14 hits).
Only use if the Warriors dont reach the obstacles with a Chaos Attack.

Hermit 7/10

The all-in-one class, Dmg/AOE/SA/ST/PUSH (Damage, Area of Effect, Status Alignment, Stun, Push Away) they got it all, their only downfall is the No-Movement problem, always station them on the top screen, ALWAYS. Their Law Attack can create havoc on the map pushing monsters to lower echelons where warriors can hit them.
They can break obstacles really fast doing 70%-100% dmg on them in 1 go(4-7 hits).

Other Classes 1/10...

Wizards/Priests are of no use unless you fighting just in Leveling mode which is used for getting items and exp.
Archers dont do great dmg, cant move, and its only usage is for long range hits, which you can compensate with 2 warriors on each corner.

Apart from that, thats for the classes.

Now on the normal battle maps.

Small tips on how to get things and moving around.

First always start the maps using the key items for the knights which are available to get on the map, use them, then exp/mp the turn, and change your knights for warriors/knights/duelist, to get the obstacles broken, and moving around after breaking them.
Normally there's always more than 3-5 key items on the starting maps, i recommend going all the way to turn 10, breaking obstacles and getting items/keys.
After you have gotten or made sure you got all the items, kill the mobs.

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Tip.

The way to know if there are key items are, when you are deploying your knights on the deploying screen(lower one) you can browse around the obstacles and see if they got key or weapon items. After you have broken all, they should re spawn again with the exception of bridges.

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This is the way to get all the key items on all maps, theres no other way, some maps will take you all the way to turn 15-19 to get all the key items, some are as easy as turn 8. This takes some time, buts its only for those who want to get the real deal knights who are the kick ass on this game.

Now on how to use the Knights correctly.

Normally as any other RPG, we go for the high lvl characters, but being high lvl dosnt mean they are useful, some have low VIT, and some got low Chaos/Law attributes.

The Chaos/Law bars (red and blue bars on the status window) depending on how high they are, its how fast they charge the skills on the weapon items, on the battle map, when you take a weapon to them it depends on the Chaos Law status how fast they charge and how slow they charge the skills, l8r in game you will get knights which charge in less than 1 sec the attack bars.

Some times low lvl knights are prompted to get high lvl limits, which is something good, they are useful to Tran Soul them to another char to increase their lvl-Limit or use them to make them the Ace of Spaces, sacrificing a high lvl char with Huber stats to them.

Now about Tran Soul.

I recommend it to do it on your first run, because you wont get all the knights and you wont get the pretty ending.
Its useful if you sacrifice some chars of other classes for the ones you will always use, always keep in mind the race they belong to, depending on the race the trans soul you make could be useless, l8r in game you will get knights which are Aces and you wont need your Tran souled ones, but some times they are useful because of the high stats you could sacrifice them for the low lvl chars.

Anyway i think you can get the idea with this small guide i just wrote down.

ill keep updating it as i go on my second run.

if you got any question don't bother asking, ill answer right away XDXD.